Yes, serio-comic can be considered a form of comedy. It combines serious and humorous elements to create a unique and often engaging comedic experience.
Serio-comic often combines serious themes with humor, while drama is typically more intense and focused on serious emotions. So, the contrast lies in the tone and approach to presenting the story.
Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.